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The Diet That Could Slash Your Cancer Risk by Nearly 25 Percent
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Cutting back on meat is a well-known way to reduce the risk of cancer, and a new study found evidence that the risk reduction might be greater than you think.
A study conducted by researchers from the Adventist Health Study-2 (AHS-2) found that some vegetarian diets are linked to significantly lower rates of cancer.
The researchers followed 79,468 Seventh-day Adventists from the United States and Canada over an average of 7.9 years.
Stock image of vegetables.
Stock image of vegetables.
Photo by Aamulya / Getty Images
Promising Results
All participants were cancer-free at the start of the study, which assessed diet through a validated food frequency questionnaire and tracked new cancer diagnoses via state and provincial cancer registries.
Some of the groups involved showed nearly a one-quarter reduction in risk compared with nonvegetarians.
"There are many indications that more fruit and vegetables and less meat may be protective for certain cancers," study author Gary Fraser told Newsweek in an email.
"Vegans exemplify such dietary choices more than any other group, perhaps. So, evaluating their risk 'adds to the story', potentially showing consistency with other work."
What the Study Found
Overall, vegetarians had a 12% lower risk of all cancers combined and an 18% lower risk of so-called "medium-frequency" cancers, which include melanoma, thyroid, ovarian, pancreatic, stomach, lymphoma and other less common sites.
When broken down by diet type, vegans showed an even larger benefit—a 24% lower risk of developing any cancer. Lacto-ovo-vegetarians and pesco-vegetarians also had reduced risks to a lesser extent.
Specific cancer sites where vegetarians saw notable reductions included:
Colorectal cancer : 21% lower risk among all vegetarians, with pesco-vegetarians showing a 39% reduction.
: 21% lower risk among all vegetarians, with pesco-vegetarians showing a 39% reduction. Stomach cancer : 45% lower risk in vegetarians overall.
: 45% lower risk in vegetarians overall. Lymphoproliferative cancers (lymphomas and lymphoid leukemias): 25% lower risk in vegetarians, with reductions seen in both vegans and lacto-ovo-vegetarians.
"Pesco-vegetarians are like vegans in consuming no red meats or chicken, and also substantially make up for that with more fruits and vegetables," Fraser told Newsweek.
"But so do lacto-ovo-vegetarians, yet the pesco-vegetarians probably do a little better.
"At this point, we can only speculate that long-chain n-3 fatty acids may offer some additional protection.
The vegans do not do quite so well for this cancer, perhaps due to their absence of dairy milk and its calcium content."
Weight and Diet Composition
Adjusting for body mass index (BMI) reduced but did not eliminate the associations, suggesting that part of the protective effect could be due to the lower average BMI seen in vegetarians.
The researchers also noted that plant-based diets are typically higher in fruits, vegetables, nuts and legumes, which provide phytochemicals thought to protect against cancer, and exclude red and processed meats, which are recognized risk factors for certain cancers.
No Evidence of Harm
Importantly, the study found no indication of increased risk for any cancer type among vegetarians.
For some cancers, particularly gastrointestinal types, the researchers said the evidence of protection was consistent with previous findings.
"Many of the authors were already vegetarian, either lacto-ovo- or pesco-," Fraser told Newsweek.
"I am not aware that any of us have moved further toward veganism, perhaps because our data do not suggest much benefit in vegans from total mortality. [...]
"Vegetarian diets seem to allow significantly more people to achieve old age, but once there, being too strict may no longer be optimal. This needs more research."
What's Next
The researchers were clear that the study cannot prove cause and effect, but they called the results "strong and persuasive" enough to suggest that vegetarian diets may offer real public health benefits with minimal downside.
